Blood is the “river of life” that surges within us. It transports everything that must be carried from one place to another within the body- nutrients, wastes (headed for elimination from the body) and body heat through blood vessels. Long before modern medicine, blood was viewed as magical, because when it drained from the body, life departed as well.

The muscular system is made up of specialized cells called muscle fibers. Their main function is contractibility. Muscles, connected to bones or internal organs and blood vessels, are in charge for movement. Almost every movement in the body is the outcome of muscle contraction.

The major endocrine organs of the body include the pituitary, thyroid, parathyroid, adrenal, pineal and thymus glands, the pancreas, and the gonads. The regulatory functions of the nervous and endocrine systems are similar in some aspects, but differ in such ways.

The skeletal system consists of bones and their associated connective tissues, including cartilage, tendons, and ligaments. It consists of dynamic, living tissues that are capable of growth, detect pain stimuli, adapt to stress, and undergo repair after injury.

The nervous system is involved in some way in nearly every body function. All the sensations, actions, and emotions are made possible by the nervous system, which consists of the brain, spinal cord, nerves, and sensory receptors.

The integumentary system consists of the skin and accessory structures, such as hair, nails, and glands. The integumentary system is recognizable to most people because it covers the outside of the body and is easily observed.

The trillions of cells in the body require an abundant and continuous supply of oxygen to carry out their vital functions. We cannot “do without oxygen” for even a little while, as we can without food or water.